Search for Gravitational Waves from the Coalescence of Subsolar-Mass Binaries in the First Half of Advanced LIGO and Virgo’s Third Observing Run

We present a search for gravitational waves from the coalescence of subsolar-mass black hole binaries using data from the first half of Advanced LIGO and Virgo's third observing run. The observation of a subsolar-mass black hole merger may be an indication of primordial origin; primordial black holes may contribute to the dark matter distribution. We search for black hole mergers where the primary mass is 0.1 – 7 M⊙ and the secondary mass is 0.1 – 1 M⊙. A variety of models predict the production and coalescence of binaries containing primordial black holes; some involve dynamical assembly, which may allow for residual eccentricity to be observed. For component masses > 0.5 M⊙, we also search for sources in eccentric orbits, measured at a reference gravitational-wave frequency of 10 Hz, up to e10∼ 0.3 . We find no convincing candidates and place new upper limits on the rate of primordial black hole mergers. The merger rate of 0.5–0.5 ( 1.0 – 1.0 ) M⊙ sources is < 7100 ( 1200 ) Gpc−3 yr−1. Our limits are ∼ 3 – 4 times more constraining than prior analyses. Finally, we demonstrate how our limits can be used to constrain arbitrary models of the primordial black hole mass distribution and merger rate.